The Internet's dominant online video site, whose content has been free to watch since its inception, added monthly fees to generate a second source of revenue to support its content creators.

The pilot subscription program launched with 30 paid channels spanning the programming gamut, from familiar children's fare to British TV and documentary films to entertainment offerings targeting specific audiences, such as "Gay Direct" and the Alchemy's rap battle network.

"This is really just the beginning," said Malik Ducard, YouTube's director of content partnerships. "We'll also be rolling out more paid channels in the coming weeks."

Some YouTube channels, such as "Sesame Street," will offer its subscribers full episodes. The UFC will provide access to classic fights. As with cable TV, the channels may or may not feature ads -- at the discretion of the channel creator.

"We're really going back to the beginning of when YouTube turned its lights on, unleashing that world of creativity," Ducard said. "We think the rollout of the paid subscriptions ... helps to further that goal."

Subscribers can access the channels on their computers, smartphones, tablets and Internet-connected televisions. Over time, other YouTube content creators will be able to opt into the subscription program, the company said.